Technical Field
The present invention concerns a method of assessing a wind power installation, in particular assessing rotor blades of a wind power installation, and a corresponding assessment apparatus.
Description of the Related Art
In particular the present invention concerns the assessment of a horizontal-axis wind power installation comprising a pylon and a pod with a rotor and rotor hub with a plurality of rotor blades, as is shown in FIG. 3.
Rotor blades of a wind power installation can nowadays be of lengths of up to 60 m and in that case are exposed to fluctuating wind loads and sometimes even storms. In that case considerable loadings occur on the rotor blade, and in particular on rotor blades which are made entirely or partly from a composite fiber material like for example glass fiber materials can be damaged in particular by such overloads. Such damage can be recognized for example by crack formations. It is important that such cracks or other indications of damage are recognized early in order to avoid major damage by the rotor blade being replaced or if possible repaired.
For that reason a regular inspection of rotor blades for any symptoms of damage can be appropriate. Such investigations are also referred to as assessments or appraisals. In principle such assessments can also be performed on other components of a wind power installation like for example the pylon or the pod. To perform rotor blade assessment, the procedure involved is frequently that the wind power installation is stopped and the surfaces of the rotor blades are inspected by means of equipment like cherry pickers, working platforms or abseiling devices. Such inspections are time-consuming and costly and the described operations at such heights also involve a risk for the service workers who perform those inspections, namely assessment operations, namely being a risk due to working at height.
As state of the art attention is directed at this juncture generally to the following documents: DE 10 2006 032 387 A1, DE 103 23 139 A1, DE 10 2008 053 928 A1, DE 10 2009 009 272 A1 and WO 2010/051 278 A1.